In marking systems such as Xerography or other electrostatographic processes, a uniform electrostatic charge is placed upon a photoreceptor surface. The charged surface is then exposed to a light image of an original to selectively dissipate the charge to form a latent electrostatic image of the original. The latent image is developed by depositing finely divided and charged particles of toner upon the photoreceptor surface. The toner may be in dry powder form or suspended in a liquid carrier. The charged toner, being electrostatically attached to the latent electrostatic image areas, creates a visible replica of the original. The developed image is then usually transferred from the photoreceptor surface to a final support material such as paper and the toner image is fixed thereto to form a permanent record corresponding to the original.
In these electrostatic marking systems, a photoreceptor surface is generally arranged to move in an endless path through the various processing stations of the Xerographic process. Sometimes, the photoreceptor or photoconductor surface is in the form of an endless belt and in other systems it's in the form of a drum. Since the photoreceptor surface is reusable when the toner image is transferred to a final support material such as paper, the surface of the photoreceptor is cleaned by a blade and/or brushes and prepared to be used once again in the copying process. In this endless path, several Xerographic related stations are traversed by the photoconductive belt or drum.
In one embodiment after the transfer station, a photoconductor cleaning station is sequentially next. This cleaning station may comprise a cleaning brush and/or a cleaning or doctor blade which is used to remove residual debris from the belt or drum photoconductive surface. A film or debris on the photoconductor surface is generally caused by the toner being impacted onto the belt by the cleaning brushes or other components in the marking system.
When a blade cleaner is used to clean a photoreceptor surface, once the machine cycles out or slows down, the blade may stick and slip on this surface through difference frequencies, causing an audible noise known as grunting. At the end of the printing or copying job, interaction between the photoreceptor surface and the blade normally takes place. As noted, it is this stick and slip blade motion which produces this annoying grunt noise. This noise ultimately results often in unscheduled service calls and reduces customer satisfaction and sometimes productivity.
There are known various noise masking systems used in image-forming apparatus such as those in Fuji Xerox U.S. Pat. No. 5,784,670 (Sasahara I) and U.S. Pat. No. 5,930,557 (Sasahara II). However, none of these known systems deals with the noise problems caused by the interaction of a cleaning blade with a photoreceptor surface. In Sasahara I, his invention deals with a noise masking system in an image forming apparatus such as a laser beam printer or a copying machine having a drive mechanism acting as a noise generation source during operation. The noise masking system comprising a masking sound generator for generating a sound to mask the noise and masking sound control means which controls the masking sound generator to generate a masking sound of a frequency range including a main component frequency of the noise. The masking sound thus generated is of a frequency range from a lower limit frequency to an upper limit frequency in a critical band of the main component frequency of the noise. The noise masking system masks noise to eliminate a psychological unpleasant feeling caused by frequency fluctuation.
In Sasahara II, his invention deals with a noise masking system in an image forming apparatus such as a laser beam printer or a copying machine having a drive mechanism acting as a noise generation source during operation. The noise masking system comprising a masking sound generator for generating a sound to mask the noise and masking sound control device which controls the masking sound generator to generate a masking sound of a frequency range including a main component frequency of the noise. The masking sound thus generated is of a frequency range from a lower limit frequency to an upper limit frequency in a critical band of the main component frequency of the noise. Both Sasahara patents deal with masking a noise rather than eliminating or reducing the noise.